Re: [Xen-devel] Design doc of adding ACPI support for arm64 on Xen - version 4

[Shannon Zhao <shannon.zhao@xxxxxxxxxx>]

On 2015/8/20 19:28, Roger Pau Monné wrote:
> El 20/08/15 a les 13.22, Shannon Zhao ha escrit:
> > Hi Roger,
> >
> > On 2015/8/20 16:20, Roger Pau Monné wrote:
> > > El 20/08/15 a les 5.07, Shannon Zhao ha escrit:
> > > > On 2015/8/19 23:02, Roger Pau Monné wrote:
> > > > > El 19/08/15 a les 14.13, Shannon Zhao ha escrit:
> > > > > > XENMAPSPACE "XENMAPSPACE_dev_mmio". The usage of this hypercall
> > > > > > parameters:
> > > > > > - domid: DOMID_SELF.
> > > > > > - space: XENMAPSPACE_dev_mmio.
> > > > > > - gpfns: guest physical addresses where the mapping should appear.
> > > > > This is not complete, you have forgotten to add the idxs field,
> > > > Sorry, I didn't use the idx for the mmio region mapping. What's the idx
> > > > useful for here?
> > > I've already posted this in the previous version, and you agreed on the
> > > interface and the usage of the fields, please see:
> > >
> > > http://marc.info/?l=xen-devel&m=143986236212359
> > >
> > > The idxs field is explicitly mentioned there with it's usage.
> > Yeah, I said I will add the description of hypercall parameters.
> > It seems that we are talking about a different parameter.
> > To map the mmio region, I reuse the struct xen_add_to_physmap and there
> You should also take into account xen_add_to_physmap_batch (or are you
> planning to issue an hypercall for every single MMIO page that you want
> to map?), but anyway the idx(s) field is there in both structs.
Yeah, current approach is to issue an hypercall for every single MMIO 
page. But if we want to batch map MMIO pages, I think it needs the size 
parameter and what's idxs useful for? As we map the MMIO pages 1:1, it 
seems it's unnecessary to check "idxs[i] == gpfns[i]", right?
> > is idx not idxs. Everytime Dom0 maps one page and it's mapped 1:1(guest
> > physical address is same with real physical hardware address), so it
> > only needs to tell the hypervisor the gpfn.
> IMHO, I'm not sure why we should restrict this to 1:1 (although I admit
> this is going to be the common case). Didn't we are that we are going to
> allow non 1:1 mapping of MMIO regions?
>
> If you want you can check in the hypercall handler that idxs[i] ==
> gpfns[i], and return -EOPNOTSUPP if they don't match, but I still don't
> see why this should be restricted to 1:1 mappings.
For Dom0 which get the device MMIO information from the DT or ACPI DSDT 
table. To ACPI, we don't (or can't)modify anything in DSDT table. So 
actually the MMIO regions Dom0 gets are the real physical hardware MMIO 
regions and the start address and size of them are same.
--
Shannon

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